1. Field of the Invention
The present invention relates to a key input unit including an antenna that is preferably used for an RFID system, a near field communication system (NFC), and the like, and an electronic apparatus including the key input unit.
2. Description of the Related Art
A coil antenna appropriate for a high frequency (HF) band is generally used for an NFC antenna. Japanese Unexamined Patent Application Publication No. 2010-102531 describes the configuration in which such coil antenna is provided in a housing of an electronic apparatus. Japanese Unexamined Patent Application Publication No. 2006-85288 describes an external RFID communication device that is used by attaching an antenna unit with a USB connector to a USB terminal of a notebook PC. Further, WO 2007/000807 describes a tag that is bonded to a metal housing of the notebook PC and that makes communication.
In an information processing apparatus described in Japanese Unexamined Patent Application Publication No. 2010-102531, an NFC antenna module is arranged between a touch pad of a notebook PC and a bottom plate metal portion provided under the touch pad. The NFC antenna module performs near field communication with an IC card if the IC card is held in the vicinity of the touch pad.
If the touch pad uses an electrostatic capacity system, for example, a large number of metal patterns such as capacitor patterns are incorporated therein. The metal patterns inhibit formation of a magnetic field of the NFC coil antenna, resulting in a problem that preferable antenna characteristics are not obtained easily. In recent years, the metal housing tends to be widely used as a result of putting emphasis on strength and design. Due to this, it becomes difficult to arrange the coil antenna at a position at which the coil antenna is not subject to an electromagnetic shield action.
The external RFID communication device described in Japanese Unexamined Patent Application Publication No. 2006-85288 is a projecting attachment with respect to the notebook PC. Therefore, if impact due to dropping or the like is applied to the projecting portion, the external RFID communication device is easy to be broken.
In the tag as described in WO 2007/000807, a tag (antenna) projects from the metal housing. Due to this, operability is inhibited and the tag is easy to be peeled off.